Fig. 3. Gene expression in cumulus cells and in individual embryos cloned from cumulus cell nuclei. Cumulus cells were enzymatically separated from cumulus cell-oocyte complexes. Cumulus cells exhibit abundant expression of Hsh, Ptgs2 and Tnfsg6 genes but expression of these genes is not detectable in all cumulus clones regardless of their extent of development in vitro (Fulop et al., 1997a; Fulop et al., 1997b; Joyce et al., 2001). Ghost bands (marked with an asterisk) do not correspond to expected products and are presumed to be PCR artifacts. A small amount of Oct4, Dppa3, Dppa5 and Pramel7 expression detected in cumulus cell sample is likely to be the result of contamination by mRNAs from oocytes damaged during the isolation procedure. Oct4 expression is clearly limited to the oocyte in the follicle (Pesce et al., 1998). Pre-morula pm8, morula m2 and blastocysts b4 and b14 are examples of incompletely reprogrammed cumulus clones. A full summary of gene expression is shown in Fig. 4.

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